In general, an application program transmitted over the Internet (hereinafter referred to as a web application) is configured of HTML (HyperText Markup Language) files, image files, and the like (for example, see Patent Document 1).
As illustrated in FIG. 1, in a production environment of a web application (1100), it is typical that in the lower-order layer of a particular folder such as “Root” (1110), folders according to the producer's convenience such as “main” (1120), “image” (1130) and the like are created, and resources necessary for such folders are placed therein. In the example of FIG. 1, HTML document files such as A.html (1122) and B.html (1124) are placed in the main folder (1120), which is in the lower-order layer of the root folder (1110) and image files such as a.jpg (1132), b.png (1134), c.jpg (1136), and d.gif (1138) are placed in the image folder (1130).
As such a hierarchical structure is provided, resource reference in HTML documents is often described by a relative path based on the premise of the directory structure of FIG. 1, as illustrated in FIG. 2. FIG. 2 illustrates an exemplary description of a relative path (1210) in the case of referring to a.jpg (1132) laced in the image folder (1130) from A.html (1122) placed in the main folder (1120).
The web application (1100) created in this manner is uploaded to an application server connected with the Internet in a state of maintaining the directory structure of FIG. 1, and is supplied to a receiver.
On the other hand, an application program transmitted by data carousel transmission (hereinafter referred to as a data broadcast application), used in data broadcasting, is configured of BML (Broadcast Markup Language) files, image files, and the like (for example, see Patent Document 2). There is also a case where HTML document files are used instead of BML document files.
As illustrated in FIG. 3, in the production environment of a data broadcast application (1300), it is necessary to create folders in module units such as “app1” (1320) and “app2” (1330) in the lower-class layer of a particular folder such as “Root” (1310), and to place resources together for each acquisition unit in those folders, depending on the structure of transmission data. In the example of FIG. 3, A.html (1122), a.jpg (1132), and b.png (1134) are placed in the app1 folder (1320), and B.html (1124), a.jpg (1132), c.jpg (1136), and d.gif (1138) are placed in the app2 folder (1330).
As such, as illustrated in FIG. 4, in data carousel transmission (1400), two types of messages are mainly used, namely DDB (Download Data Block) including real data of a data broadcast application, and DII (Download Info Indication) storing directory information of DDB.
DII indicates index information to be transmitted within the data carousel. Further, information of a plurality of modules can be described in one DII. When a receiver receives the DII, it recognizes the structure of a module. In the DII (1410) of FIG. 4, information such as module id 1412 and module name (4141) is described for each of the modules m1, m2, . . . , mk (1410-1, 1410-2, . . . 1410-k, k=1 to n).
DDB corresponds to each block of a module. The DDB (1420) of FIG. 4 is configured such that RL (Resource List, 1420-1), in which names of resources stored in the module such as A.html (1422), a.jpg (1424), and b.png (1426) are listed, is placed following the header information. Further, real data of A.html (1420-2), a.jpg (1420-3), and b.png (1420-4) are placed following the RL (1420-1).
As schematically illustrated in FIG. 4, as the modules in blocks are transmitted cyclically by data carousel transmission, a receiver obtains DDB based on the DII and reconstructs the target module.
It should be noted that the transmission sequence of DDB and DII is arbitrary. However, as DII stores data equivalent to index information, it is transmitted at relatively high frequency.